Walk-in bathtubs comprise high tub walls with a high built in seat and a side door, allowing the user to walk into the tub from the side and sit down without having to climb down into a low bath tub. FIG. 1 shows a typical example of a walk-in bathtub in accordance with the prior art. Walk-in tubs are particularly suited for individuals who have physical limitations that make it difficult or dangerous to climb into and out of a regular, low bathtub or to stand up in a shower for extended periods of time. Such limitations might include physical disabilities or simply the reduced strength, balance and range of motion that typically occur with advancing age. Walk-in tubs are not only easier to enter and exit than conventional bathtubs, they also reduce the chances of slips and falls compared to conventional tubs and showers.
In addition to safety, the ease of entering the tub via the side walk-in door also provides users with independence, allowing them to bathe without the assistance of another person when getting into and out of the tub.
Acrylic is the preferred material for conventional bathtub manufacturers. Acrylic is germ and stain resistant, has good heat retaining qualities and is durable. Because acrylic is non-porous, mildew and algae cannot stick to it. It wipes clean with common household non-abrasive cleaners. Even grease, oils, hair dyes and cosmetics that would stain other materials can be easily removed with rubbing alcohol.
However, because of their depth, walk-in bathtubs are typically made from gel-coated fiberglass, which does not offer the advantages of acrylic in terms of heat retention, stain resistance and strength. The reason for using fiberglass in manufacturing walk-in tubs lies in the technical difficulties in forming the deep basin of the tub with a single sheet of acrylic. With seat heights approaching 17 inches above the tub floor, acrylic has a tendency to tear during the vacuum forming process or become excessively thin at the bottom, comprising its ability to hold the requisite water weight.
Therefore, a need exists for a method of vacuuming forming walk-in bathtubs from a single sheet of acrylic.